(1) Field of the Invention
The present invention relates to a method and system for making composite materials. In particular, the present invention relates to a method and system for making composite materials using wood particles and a binder. The method and system allows for controlled, simultaneous feeding of the particles and binder to form a uniform mat. The system and method also provides for compaction of the mat immediately after formation of the mat prior to setting of the binder.
(2) Description of the Related Art
The related art has shown various types of apparatuses and methods for making composite panels from particles. In general these processes provide means for mixing binder with particles, producing a uniform mat with this furnish, and then consolidating it with pressure. Many processes also combine heat with pressure not only to cure the binder but also to make the particles more compliant to compression. The related art thus contains different means for mixing ingredients, forming into mats, and applying pressure, with or without introducing heat. Illustrative are U.S. Pat. No. 2,854,372 to Yan et al; U.S. Pat. No. 3,256,215 to Knox; U.S. Pat. No. 3,308,218 to Wiegand et al; U.S. Pat. No. 4,097,965 to Gotchel et al; U.S. Pat. No. 4,255,108 to Bleymaier et al; U.S. Pat. No. 4,701,294 to Radwanski et al; U.S. Pat. No. 4,865,788 to Davis; U.S. Pat. No. 5,102,595 to Tilby; and U.S. Pat. No. 5,108,678 to Hirasaka et al.
Yan et al describe a method of forming a board with elongate particulates which are deposed essentially parallel to the surfaces and one edge of a panel. The method involves edge-forming as opposed to conventional flat-forming. Particles previously coated with binder, are dropped into a hopper fitted with baffles that disperse the particles as they fall between two moving endless parallel steel bands spaced apart vertically. Thus confined, the elongate particles are forced to orient themselves essentially parallel to the surfaces of the belts as well as parallel to the continuously forming edge of the mat. The mat is then conveyed into a hot press for consolidation with pressure in the face direction.
Knox shows a process for incorporating finely ground fillers to a polyurethane froth by comixing during formation of the froth. Alternatively, for coarser fillers, a froth is added as a layer to the top of a preformed mat of the filler and driven in by platen or mold pressure.
Wiegand et al describe an air-lay system for forming a fibrous mat in which a tackifying material is added to prevent intermeshing and thereby produce a low density mat for later consolidation by normal means.
Gotchel et al describe an apparatus and method for dry-forming fibrous structures by a system of drums with projections that individualize fibers from a laminate feed and blends different length fibers into a uniform mat using air flow to control the passage of fibers.
Bleymaier et al in eliminating the use of pneumatic transport and felting, utilize a system of brush rolls to distribute finely comminuted fiber into a mat suitable for later alignment by electric field means into a final mat for consolidating into fiberboard with directional properties.
Radwanski et al describe an apparatus and method for individualizing fibers from a fiberizable feed material and forming a pad of varying cross sections for use where absorbent materials are needed. The apparatus includes a drum surfaced with projections that disintegrate the feed material into fibers which are air entrained and blown into a forming zone with a compressed gas where other baffle-controlled gas streams direct the fibers to selected areas on a moving foraminous web, below which is a suction box to remove air from the system.
Davis describes a system of picker rolls to break up and meter bales of different types of fiber to form separate but superposed layers composed of different fibers which are then fed through blender rolls to thoroughly mix them. It is reformed into a mat with the aid of spike wheels and air pressure, given a dusting of a powdered binder and reblended through another set of picker rolls. Reformed again with spike wheels and air pressure, the mat then is overlayed with a non-woven scrim which is needled into the mat to improve properties of the product and to impart temporary integrity for handling into molds.
Tilby describes an apparatus and method for composing a mat of relatively long, straight strands such as rind strands from sugar cane processing which is comprised of a feed conveyor moving the long strands, already dried and coated with binder, to a drop zone over a pair of counter rotating rolls fitted with flicker tines which fling the strands randomly and uniformly over a moving conveyor below, ready for consolidation by conventional pressing.
Also of interest are U.S. Pat. Nos. 3,557,263, 3,671,377 and 4,172,056 all to Marra. '263 and '377 relate to a rigid composite product and to the process for preparation thereof. The process for preparing the composite product involves adding a foam precursor to a loosely formed mat of fibrous strands and allowing the expanding foam to disperse itself throughout the mat and upon curing without the introduction of heat, consolidate the product. '056 describes products of wood and resinated cement in which the components are wet-mixed mechanically and charged batch-wise to a mold for forming to a product.
Only of minimal interest are U.S. Pat. No. 1,931,570 to Brown et al; U.S. Pat. No. 2,067,251 to Taylor; U.S. Pat. No. 2,736,362 to Slayter et al; U.S. Pat. No. 3,096,227 to Van Elten; U.S. Pat. No. 3,346,682 to Thomson and U.S. Pat. No. 5,114,631 to Nyssen et al.
Brown et al show a means of forming panels with excelsior and a cementitious binder in which the long strands are first reduced in length, gathered into a fluffy mat by spike wheels and air pressure, gradually compressed between roll-backed belts, flooded with excess binder which is squeezed out by opposed rollers, cut to length, and stacked in a batch press under pressure until the binder sets.
Taylor shows a method of extruding molten plastic through nozzles to produce fibers which are then collected loosely on a rotating drum for later spinning into yarn.
Slayter et al shows a method of making fiberglass insulating mats by first producing mineral fibers and forming them directly into a veil by feeding them between cooperating rollers. The veil is diffused with powdered binder blown in and vibrated to improve distribution and then folded on itself to produce a continuous batt. The later heating operation cures the binder.
Thomson shows a method of making a cigarette filtering medium by first extruding very fine plastic filaments and then forming them with roller pressure into a tape which is later expanded to a bulky material for fashioning into a filter.
Nyssen et al describe a process for making non-woven fabrics by spinning molten polymer under supply pressure radially from a plurality of openings mounted on a rotating nozzle head. A hot gas stream aids in propelling the spun fibers onto a circulating, air-permeable carrier.
The above representative review of related art describes various ways of forming composites from fibrous particles. There remains a need for a method and system for producing composite materials comprised of particles which allows for the simultaneous deposition of particle and binder into a mat so that immediate consolidation can occur without further manipulation, thus permitting the use of fast, selfcuring binders to achieve a more versatile and more efficient processing system in which an oscillating shield is used to create a unilayer stream of particles for easy coating with binder and for uniform distribution of furnish in the forming zone.
Further, there remains a need for an apparatus and method for forming composites from fibrous particles which, in conjunction with co-pending applications relating to the production of fibrous strands from waste or unwanted wood, would allow small businesses to utilize such unused resources, scattered and essentially worthless "as is, where is", thus contributing to a local economy while promoting environmentally favorable practices.